I've been switching back and forth between using MM and Gmail as my primary mail account for a few years. When I had Gmail set up as the primary account, I'd set up MM to forward mail I received at that address to Gmail - and vice versa. I've decided to switch to Gmail again and gradually phase out my MM address over the next year. I know how to set Gmail IMAP up with Mail.app. My question is how to retain all of my archived messages from both MM and Gmail when I make the switch. I've had Gmail forwarding to MM for the past 1.5 years, and I have a rule set up so that every message I receive at MM is copied to a folder called "Archive". So every message I've received at the Gmail address over the past year should be stored on the MM server. There are also 1.5 years worth of messages I received directly to my MM address, although this is a much smaller number because I don't advertise that address publicly. If I simply switch to Gmail without dragging any messages from the MM Archive folder, I'll retain all of the Gmail mail for the past 1.5 years. However, I would lose all of the MM mail during that period. BUT, if I drag all of the messages from the MM Archive folder to Gmail, won't I end up with duplicates of all of the Gmail messages (since there is already a copy of the Gmail messages on the Gmail server, and I'd be adding another copy of each Gmail message that was forwarded from Gmail to MM)? Is this making sense? Any ideas?